Shape Recovery Behavior of PETG Structures in 4D Printing

Four-dimensional (4D) printing combines additive manufacturing with stimuli-responsive behavior, enabling structures to recover their original geometry under external activation. This work investigates the shape recovery of polyethylene terephthalate glycol-modified (PETG) structures fabricated by fused deposition modeling (FDM). To evaluate the influence of printing conditions, an orthogonal Taguchi design was employed considering key parameters such as layer height, extrusion width, and nozzle temperature. The specimens underwent a thermomechanical cycle comprising deformation, fixation, and thermal recovery. Shape recovery was quantified through the shape-recovery ratio (𝑅𝑟) and maximum shaperecovery rate (𝑉𝑚), providing a systematic framework for assessing how process parameters govern recovery performance. The study establishes a methodological basis for understanding PETG as a shapememory material in 4D printing, with potential applications in adaptive structures, biomedical devices, and aerospace systems.